Reconfigurable Tunable Broadband Antenna Components

Modern radio systems (e.g., for television and radio broadcasting, mobile networks (e.g., 4G, 5G, etc.), satellite communications, Wi-Fi and wireless networks, military and defense applications, the Internet of things (IoT), etc.) often have high bandwidths and are frequency-agile to avoid congestion, mitigate jamming, and/or match signals to channel propagation characteristics. The antennas used for such systems are designed to transmit and receive radio waves effectively, covering different frequency ranges and applications.

Modern antennas are designed to operate across a wide range of frequencies, from very low frequency (VLF) bands used in submarine communication to millimeter waves used in advanced radar and 5G technology. Antennas can be omnidirectional (receiving signals from all directions) or directional (focusing on a specific direction), depending on the application.

Gain refers to the ability of the antenna to direct or concentrate radio frequency energy in a particular direction, enhancing signal strength and reception quality. The bandwidth of an antenna is the range of frequencies over which the antenna can effectively operate. Wideband antennas can handle multiple frequencies simultaneously, which can be crucial for modern communication systems.

The radiation Q factor of an antenna is a measure of the bandwidth of the antenna relative to its size. A lower Q factor indicates a wider bandwidth, while a higher Q factor indicates a narrower bandwidth.

The well-known Chu-Harrington limit defines the trade-off between the size of an antenna and its bandwidth and efficiency. The Chu-Harrington limit is a theoretical limit that imposes constraints on how small an antenna can be made while still maintaining acceptable performance characteristics.

With advancements in materials and technology, antennas have become more compact and integrated into devices, which can compromise performance. The Chu-Harrington limit is particularly relevant for electrically small antennas, which are antennas whose physical dimensions are much smaller than the wavelength of the operating frequency. As antennas become smaller, their bandwidth tends to decrease and their efficiency can drop. Specifically, as the size of an antenna decreases, the Q factor increases, meaning that the antenna becomes more narrowband. Thus, there is a fundamental limit on how much an antenna's size can be reduced without sacrificing bandwidth.

Designers typically balance the desire for small antenna size with the need for sufficient bandwidth and efficiency. The design process often involves trade-offs, where improving one aspect can degrade another.

Accordingly, there is a need for improvements.

This summary represents non-limiting embodiments of the disclosure.

In some aspects, the techniques described herein relate to an antenna component, including: a first circuit including a first selector coupled in series to a first memory cell; a second circuit including a second selector coupled in series to a second memory cell; a first antenna element coupled to the first circuit; a second antenna element coupled to the second circuit; and control circuitry coupled to the first circuit and the second circuit, wherein the control circuitry is configured to use the first circuit to select the first antenna element and use the first circuit to select the second antenna element.

In some aspects, at least one of the first memory cell or the second memory cell is nonvolatile.

In some aspects, the antenna component further includes: a first wire coupled to a first terminal of the first circuit, to a first terminal of the second circuit, and to the control circuitry; a second wire coupled to a second terminal of the first circuit and to the control circuitry; and a third wire coupled to a second terminal of the second circuit and to the control circuitry, and wherein the control circuitry is configured to access the first circuit using the first wire and the second wire, and to access the second circuit using the first wire and the third wire.

In some aspects, the antenna component further includes: a reference plane; and a capacitor coupling at least one of the first wire, the second wire, the third wire, the first circuit, or the second circuit to the reference plane.

In some aspects, the antenna component further includes: a reference plane; and a capacitor coupling at least one the first circuit or the second circuit to the reference plane.

In some aspects, the first antenna element is connected to the first memory cell of the first circuit and the second antenna element is connected to the second memory cell of the second circuit.

In some aspects, the techniques described herein relate to an antenna component, including: a switching fabric including: a plurality of wires, and a plurality of selector-switch circuits, each of the plurality of selector-switch circuits being addressable by a respective unique pair of wires of the plurality of wires; and a plurality of antenna elements, wherein each antenna element of the plurality of antenna elements is coupled to the switching fabric to substantially prevent direct current on any of the plurality of wires from flowing through the plurality of antenna elements and to substantially prevent radio-frequency signals fed to or flowing through any of the plurality of antenna elements from flowing through the plurality of wires.

In some aspects, each selector-switch circuit of the plurality of selector-switch circuits includes a respective selector coupled in series to a respective memory cell. In some aspects, the respective memory cell is nonvolatile.

In some aspects, each selector-switch circuit of the plurality of selector-switch circuits includes: a respective first outer terminal coupled to a first wire of the respective unique pair of two wires; and a respective second outer terminal coupled to a second wire of the respective unique pair of two wires.

In some aspects, each selector-switch circuit of the plurality of selector-switch circuits further includes: a respective inner terminal coupled to a respective antenna element of the plurality of antenna elements.

In some aspects, each selector-switch circuit of the plurality of selector-switch circuits includes a respective memory cell, and the respective inner terminal couples the respective antenna element to the respective memory cell.

In some aspects, the antenna component further includes a phase shifter coupled to the plurality of antenna elements.

In some aspects, the plurality of antenna elements is arranged in a non-planar configuration.

In some aspects, the antenna component further includes one or more hardware elements coupled to the switching fabric and/or the plurality of antenna elements, wherein the one or more hardware elements are configured to substantially prevent the direct current on any of the plurality of wires from flowing through the plurality of antenna elements and/or to substantially prevent the radio-frequency signals fed to or flowing through any of the plurality of antenna elements from flowing through the plurality of wires. In some aspects, the one or more hardware elements include at least one of: a capacitor, an inductor, a split-ring resonator, a low-pass filter, a high-pass filter, a band-pass filter, a hybrid, a directional coupler, a band-stop filter, a notch filter, a splitter, a transformer, a waveguide filter, a stub, or a resistor.

In some aspects, the antenna component further includes: control circuitry coupled to the switching fabric and configured to use the plurality of wires to configure the plurality of selector-switch circuits to configure the plurality of antenna elements.

In some aspects, the techniques described herein relate to a method of using an antenna component, the method including: the control circuitry configuring the antenna component using the plurality of wires to configure the plurality of selector-switch circuits.

In some aspects, the method further includes: before the control circuitry configuring the antenna component using the plurality of wires to configure the plurality of selector-switch circuits, performing a calculation to determine a configuration of the plurality of selector-switch circuits.

In some aspects, the method further includes: before the control circuitry configuring the antenna component using the plurality of wires to configure the plurality of selector-switch circuits, retrieving a configuration of the plurality of selector-switch circuits from a database.

In some aspects, the method further includes: adjusting a configuration of the antenna component. In some aspects, adjusting the configuration of the antenna component is based at least in part on a signal strength, a radiated power, a suppression of interference, or a suppression of jamming.

In some aspects, the techniques described herein relate to an antenna component, including: a switching fabric including: a plurality of wires, and a plurality of selector-switch circuits, each of the plurality of selector-switch circuits being addressable by a respective unique pair of two wires of the plurality of wires; and a plurality of antenna elements coupled to the switching fabric; and at least one hardware element coupled to the plurality of selector-switch circuits and configured to (a) suppress a direct current path through the plurality of antenna elements, (b) substantially prevent radio-frequency signals fed to or flowing through any of the plurality of antenna elements from flowing through the plurality of wires, or (c) both (a) and (b).

In some aspects, the at least one hardware element includes at least one of: a capacitor, a split-ring resonator, an inductor, a low-pass filter, a high-pass filter, a band-pass filter, a hybrid, a directional coupler, a band-stop filter, a notch filter, a splitter, a transformer, a waveguide filter, a stub, or a resistor.

In some aspects, the plurality of wires and the plurality of selector-switch circuits are situated in a cross-point architecture structure.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized in other embodiments without specific recitation. Moreover, the description of an element in the context of one drawing is applicable to other drawings illustrating that element.

140 140 110 110 160 160 160 Some of the drawings herein illustrate multiple instances of a feature, where each feature is designated by a common reference numeral followed by a different letter (e.g., antenna elementA, antenna elementB, selector-switch circuitA, selector-switch circuitB, capacitorA, capacitorB, capacitorC, etc.). For convenience, the detailed description sometimes refers to these features singularly or collectively using only the common reference numeral.

Disclosed herein are techniques for providing reconfigurable and tunable broadband antennas. In some embodiments, an antenna component comprises switches, selectors, and wires situated in a switching fabric. The switching fabric is coupled to a plurality of antenna elements (e.g., radiators) such that radio-frequency (RF) signals fed to or flowing through the antenna elements do not interfere with addressing/selection/configuration signals transmitted on the wires of the switching fabric, and vice versa. The switching fabric is a hardware architecture to manage the antenna elements. Using the switching fabric, individual antenna elements can be selected, addressed, and configured. The switching fabric can take any suitable form (e.g., a cross-point architecture structure or a bus-based fabric using a shared bus). In some embodiments, the isolation is effected by capacitively coupling the antenna elements to the switching fabric and/or by inductively loading the wires of the switching fabric.

In some embodiments, the switches and/or selectors include phase change materials (PCM), Ovonic threshold switching (OTS) materials, and/or resistive random access memory (ReRAM) cells in a switching fabric to allow individual or multiple antenna elements (e.g., radiators, elements of a metasurface, etc.) to be configured and/or reconfigured rapidly and to allow the frequency response and/or directionality of an overall antenna to be configured or adjusted. The antenna elements can be in a planar orientation (e.g., situated in a two-dimensional plane), or they can be distributed in a non-planar, three-dimensional configuration (e.g., they can be situated on a sphere, toroid, in a cube, etc.).

As used herein, the term “switch” refers to hardware recognized by those having ordinary skill in the art as providing switching functionality. A switch can be a single, stand-alone component, or it can be a device or circuit that includes additional circuitry, such as one or more wires, one or more power sources, one or more transistors, one or more diodes, one or more resistors, one or more capacitors, one or more relays, one or more PIN diodes, one or more inductors, and/or other hardware. For example, switches can include latching circuits, which can comprise, for example, static random access memory (SRAM) cells. As another example, switches can include a dynamic random access memory (DRAM) circuit.

1 FIG.A 100 100 100 140 140 140 140 100 140 140 is a diagram of an antenna componentA in accordance with some embodiments. The antenna componentA can be, for example, part of an overall antenna. The antenna componentA includes an antenna elementA and an antenna elementB. The antenna elementA and/or antenna elementB can be any component or components that transmit, receive, or control waves or signals transmitted or received by the overall antenna into which the antenna componentA is incorporated. For example, the antenna elementA and/or antenna elementB can be elements of a metasurface. As will be appreciated by those having ordinary skill in the art, a metasurface is a two-dimensional metamaterial designed to control various aspects of wave propagation, such as phase, amplitude, polarization, and direction. Metasurface elements are typically much smaller than the wavelength of the electromagnetic waves they interact with (e.g., on the order of one-tenth to one-hundredth of the wavelength). Metasurface elements can comprise resonant structures, such as one or more of split-ring resonators, plasmonic nanoparticles, or dielectric resonators. Examples of metasurface elements include, but are not limited to, reflectarray elements (e.g., elements that act like small, flat mirrors with adjustable phase responses, enabling beamforming in reflectarray antennas), transmitarray elements (e.g., elements designed to transmit rather than reflect the incoming waves, focusing or steering the transmitted beam), and Huygens metasurfaces (e.g., elements that simultaneously control both the electric and magnetic responses).

140 140 140 140 140 140 140 140 140 140 1 FIG.A As another example, the antenna elementA and/or the antenna elementB can be radiators. As will be appreciated, an antenna radiator emits and/or receives electromagnetic waves. When transmitting, the radiator converts electrical energy into electromagnetic waves (e.g., radio-frequency (RF) signals). When receiving, incoming electromagnetic waves induce current in the radiator, which converts them back into electrical signals. The antenna elementA and antenna elementB can be any suitable radiators, such as, for example, dipole radiators (two straight conductive elements), loop radiators, or patch radiators. As will be appreciated, the antenna elementA and antenna elementB have or are connected to ports (e.g., RF ports) that provide signals to and/or convey signals from the antenna elementA and antenna elementB. To avoid obscuring the drawing, the feeds for the antenna elementA and antenna elementB are not illustrated in, or in other drawings herein.

140 140 As another example, the antenna elementA and/or the antenna elementB can form passive or parasitic radiators that are not connected to any RF ports. As will be appreciated, a parasitic radiator couples electromagnetically to the driven element and serves to modify the radiation pattern of the driven element. The parasitic elements can have any suitable shape (e.g., a dipole). In some embodiments that include parasitic radiators, the parasitic radiators act as directors by narrowing the radiation patterns. In some embodiments that include parasitic radiators, the parasitic radiators act as reflectors by directing the radiation toward one side of the antenna. In some embodiments that include parasitic radiators, both reflectors and directors are used simultaneously.

100 110 110 110 116 116 110 116 116 116 110 116 110 120 The antenna componentA also includes a selector-switch circuitA and a selector-switch circuitB. The selector-switch circuitA has an outer terminalA and an outer terminalC, and the selector-switch circuitB has an outer terminalB and an outer terminalD. The outer terminalB of the selector-switch circuitB is coupled to the outer terminalA of the selector-switch circuitA by a wireA.

140 140 120 140 110 140 110 The antenna elementA and the antenna elementB are also coupled to the wireA. Therefore, the antenna elementA is coupled to the selector-switch circuitA, and the antenna elementB is coupled to the selector-switch circuitB.

100 130 130 130 110 110 130 120 116 110 120 116 110 120 130 120 120 140 120 120 140 100 130 140 140 The antenna componentA also includes control circuitry. The control circuitrymay comprise, for example, a voltage source, a current source, and/or any other component that allows the control circuitryto control the selector-switch circuitA and selector-switch circuitB. In the illustrated example, the control circuitryis coupled to the wireA, to the outer terminalC of the selector-switch circuitA by a wireB, and to the outer terminalD of the selector-switch circuitB by a wireC. The control circuitryis configured to use the wireA and the wireB to select the antenna elementA, and to use the wireA and the wireC to select the antenna elementB. Thus, in the antenna componentA the control circuitryis able to individually select the antenna elementA and the antenna elementB.

110 110 120 120 120 110 120 120 120 110 120 120 110 110 120 116 120 116 110 130 120 110 120 120 110 120 120 1 FIG.A 1 FIG.A The configuration of the selector-switch circuitA, selector-switch circuitB, wireA, wireB, and wireC shown inis an example of a switching fabric in which each selector-switch circuitis addressable by a respective unique pair of wires. One of the wiresof the unique pair of wiresis coupled to a first outer terminal of the selector-switch circuit, and the other of the wiresof the unique pair of wiresis coupled to a second outer terminal of the selector-switch circuit(e.g., for the selector-switch circuitA, one of the wiresis coupled to the outer terminalA and the other of the wiresis coupled to the outer terminalB). The addressing of each selector-switch circuitsis controlled by the control circuitryusing a unique pair of wires(i.e., in the example of, the selector-switch circuitA is controlled using the wireA and the wireB, and the selector-switch circuitB is controlled using the wireA and the wireC).

110 120 140 130 140 140 140 140 140 The selector-switch circuits, wires, antenna elements, and control circuitryare coupled together such that the RF path through the antenna elements(the signal(s) being transmitted or received) is substantially isolated from the direct current (DC) signals used by the addressing/selection of antenna elementsthat is implemented using the switching fabric. Similarly, the DC path used by the switching fabric (a control path) is substantially isolated from the RF signals flowing through the antenna elements. A variety of hardware elements can be included to substantially prevent the DC current flowing through the switching fabric from flowing through the plurality of antenna elementsand/or to substantially prevent RF signals fed to or flowing through any of the antenna elementsfrom flowing through the switching fabric. These hardware elements can include, for example, at least one of the following: a capacitor, an inductor, a split-ring resonator, a low-pass filter, a high-pass filter, a band-pass filter, a hybrid, a directional coupler, a band-stop filter, a notch filter, a splitter, a transformer, a waveguide filter, a stub, and/or a resistor.

120 120 120 120 140 140 120 120 120 120 120 120 120 120 120 120 120 110 110 130 140 140 In some embodiments, the wireA, the wireB, and/or the wireC are high-inductance wires, where “high-inductance” means that the wireshave sufficient inductance to substantially prevent RF signals flowing through the antenna elementA and antenna elementB from flowing through the wireA, the wireB, and/or the wireC. In some embodiments, low-pass filters are situated on or coupled to the wireA, the wireB, and/or the wireC to substantially block RF signals. In some embodiments, inductors are situated on or coupled to the wireA, the wireB, and/or the wireC to substantially block RF signals. In some embodiments, the wireshave sufficient resistance to substantially prevent RF signals from flowing along the wires. It will be appreciated that other techniques can be used to substantially isolate the selector-switch circuitA, selector-switch circuitB, and/or control circuitryfrom RF signals fed to or flowing through the antenna elementA and antenna elementB. The examples provided herein are not intended to be limiting.

1 FIG.A 110 112 114 110 112 114 112 112 112 112 112 112 114 114 As illustrated in, in some embodiments, the selector-switch circuitA comprises a selectorA coupled in series to a memory cellA. Similarly, the selector-switch circuitB comprises a selectorB coupled in series to a memory cellB. In some embodiments, the selectorA and selectorB are two-terminal devices that have a high resistance in an “off” or non-conductive state (in which the selectoracts as an open switch), and a low resistance in an “on” or conductive state (in which the selectoracts as a closed switch). When in the on/conductive state, the selectorA and selectorB allow the memory cellA and the memory cellB to be accessed/set (e.g., to a high resistance value, to a low resistance value, or to an intermediate resistance value).

112 112 114 114 112 112 112 112 The selectorA and the selectorB can be any suitable components that provide switching functionality to allow the memory cellA and memory cellB to be set. In some embodiments, the selectorA and/or the selectorB are diodes. In some embodiments, the selectorA and/or the selectorB are transistors.

112 112 In some embodiments, the selectorA and/or the selectorB are threshold switching devices. A threshold switching device is a type of electronic component that exhibits a sudden change in resistance when the applied voltage or current reaches a specific threshold value. A threshold switching device can include an active layer comprising a switching material that undergoes a structural change (e.g., formation of a conductive filament, a change in the local structure of the material, etc.) in response to an applied voltage. The material acts like an insulator (high-resistance state) in response to an applied voltage being in a range below a threshold voltage (or threshold current) and like a conductor (low-resistance state) in response to the applied voltage (or current) exceeding the threshold.

112 112 th hold In some embodiments, the selectorA and the selectorB are threshold switching devices that use chalcogenide as the switching material. When the switching material is an amorphous chalcogenide, in the high-resistance (off) state, the electronic structure of the material is such that charge carriers are not freely mobile. In this state, the switching material is said to be substantially non-conductive. The switching material stays in the high-resistance state until the applied voltage exceeds specific threshold voltage (V), at which point the material rapidly (typically in nanoseconds) switches to a conductive, low-resistance (on) state. In the conductive state, the electronic structure of the switching material allows for the rapid movement of charge carriers. In this state, the switching material is substantially conductive. When the applied voltage drops below a certain holding voltage (V), the switching material rapidly (again, typically in nanoseconds) reverts back to the high-resistance state. When the switching material comprises (or is) a chalcogenide, the threshold switching device can be referred to as an Ovonic threshold switching (OTS) device, an OTS switch, or simply an OTS.

2 2 3 2 2 th th th hold As an alternative to chalcogenides, the switching material of a threshold switching device can be (or comprise) a transition metal oxide (TMO). Transition metal oxides are compounds that have oxygen atoms bonded to transition metals. Transition metals are elements found in the d-block of the periodic table (e.g., titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc). The conductivity of TMOs can range from insulating to conducting. TMOs include NbO(niobium dioxide) and VO:Cr (chromium-doped vanadium sesquioxide). NbOhas the ability to undergo rapid (on the other of nanoseconds) metal-to-insulator transitions (MIT) and its threshold switching characteristics. Like a chalcogenide, NbOis characterized by a characteristic threshold voltage (V) at which it switches from a high-resistance state (insulating, at voltages below V) to a low-resistance state (metallic, at voltages above V). The switching is reversible, allowing the device to return to its high-resistance state when the voltage falls below a holding voltage (V).

2 3 2 3 2 3 2 3 2 3 2 3 2 3 th 2 2 3 2 3 hold 2 3 VO:Cr is vanadium sesquioxide (VO) doped with chromium (Cr). The switching behavior is provided by the MIT characteristics of VOenhanced by chromium doping. The MIT in VO:Cr can be sensitive to temperature, and the exact transition temperature can be controlled by the amount of Cr doping. The threshold voltage for switching can also be tuned based on the doping level of chromium and the properties of the VOmaterial. At or near the transition temperature, VO:Cr is in a high-resistance (insulating) state, and minimal current flows. When a voltage is applied across the VO:Cr switch and exceeds a threshold (V), the material undergoes a rapid transition from the insulating state to a metallic state, similarly to NbO. In this low-resistance state, VO:Cr behaves like a metal, with much lower resistance, allowing a large current to flow through. The VO:Cr switch remains in the low-resistance state as long as the applied voltage or current is maintained above the threshold. When the applied voltage is removed or drops below the holding voltage (V), VO:Cr reverts to its high-resistance (insulating) state, resetting the switch.

112 110 112 114 112 114 130 112 th Using threshold switching devices (e.g., an OTS device or a TMO device) as the selectorof a selector-switch circuitcan be advantageous relative to using other hardware. For example, relative to a diode, a threshold switching device has a sharper, more abrupt switching characteristic. In addition, a threshold switching device can be implemented in a small area and inexpensively. Another advantage of using a threshold switch as the selectoris that, unlike for approaches such as those that use transistors, additional control lines need not be provided to allow the memory cellto be selected. As long as the voltage applied to a selectorexceeds V, the corresponding memory cellis accessible to the control circuitry, and its state can be modified by the same voltage/current that causes the selectorto switch to the “on” or low-resistance state.

th th 112 114 112 114 110 112 114 100 100 140 In some embodiments, the threshold voltage Vof the selectoris lower than the voltage(s) required to change the state of the corresponding memory cell. For example, if Vfor the selectoris 0.7 V, and a voltage of 2 V is required to perform a particular state change of the corresponding memory cell, applying 2 V across the selector-switch circuitwill both turn on the selectorand allow the particular state change of the corresponding memory cellto be accomplished. Therefore, the antenna componentA (and other antenna componentsdescribed herein) can be implemented more compactly than conventional antennas because fewer control lines are required for addressing/selection. Furthermore, threshold switching devices such as those described above can be implemented compactly (e.g., without a CMOS process). As explained further below, the compact size of threshold switching devices allows many such devices to be provided in a switching fabric, which allows flexibility in terms of the configurations of antenna elementsthat can be supported.

100 130 112 120 112 120 112 110 120 120 130 112 112 110 120 120 130 112 112 112 114 114 130 140 140 114 114 In the antenna componentA, the control circuitryis coupled to the selectorA by the wireB and to the selectorB by the wireC. By selectively applying current to the selectorA (e.g., by applying a potential across the selector-switch circuitA using the wireA and the wireB), the control circuitrycan control the state of the selectorA (e.g., high resistance/non-conductive/off or low resistance/conductive/on). Likewise, by selectively applying current to the selectorB (e.g., by applying a potential across the selector-switch circuitB using the wireA and the wireC), the control circuitrycan control the state of the selectorB. By controlling the states of the selectorA and the selectorB, and the settings of the memory cellA and memory cellB, the control circuitrycan individually select the antenna elementA and the antenna elementB, which are connected, respectively, to the memory cellA and the memory cellB in the illustrated example.

114 114 114 114 140 114 114 140 114 130 140 In some embodiments, each of the memory cellA and the memory cellB has two states, namely, a high-resistance state and a low-resistance state. When the memory cellA (or memory cellB) is in the high-resistance state, the antenna elementA is essentially presented as an open circuit (de-selected). When the memory cellB (or memory cellB) is in the low-resistance state, the antenna elementA is selected. The memory cellB operates similarly with respect to allowing the control circuitryto select and deselect the antenna elementB.

114 114 114 114 114 114 112 112 114 114 The memory cellA and memory cellB can be any suitable devices that are operable to present at least two resistance states, depending on their programming. For example, the memory cellA and/or memory cellB can be a resistive random access memory (ReRAM), a phase-change memory (PCM), a magnetoresistive random access memory (MRAM), or any other suitable types of memory cell. The memory cellA and/or memory cellB can include the same kinds of materials as described above for the switching material of the selectorA and/or selectorB (e.g., phase-change materials, chalcogenides, etc.). In some embodiments, the memory cellA and/or the memory cellB is nonvolatile.

1 FIG.B 1 FIG.A 100 100 150 160 160 160 is a diagram of another antenna componentB in accordance with some embodiments. In addition to the components shown inand described above, the antenna componentB includes a reference plane, a capacitorA, a capacitorB, and a capacitorC.

110 110 112 114 110 116 116 118 110 112 114 110 116 116 118 100 116 110 116 110 120 140 140 120 112 112 114 114 130 1 FIG.A 1 FIG.A 1 FIG.A 1 FIG.B Like the selector-switch circuitA shown in, the selector-switch circuitA comprises a selectorA coupled in series to a memory cellA. The selector-switch circuitA has an outer terminalA, an outer terminalC, and an inner terminalA. Similarly, the selector-switch circuitB comprises a selectorB coupled in series to a memory cellB. The selector-switch circuitB has an outer terminalB, an outer terminalD, and an inner terminalB. As in the antenna componentA of, the outer terminalB of the selector-switch circuitB is coupled to the outer terminalA of the selector-switch circuitA by a wireA, and the antenna elementA and the antenna elementB are also coupled to the wireA. The selectorA, selectorB, memory cellA, memory cellB, and control circuitrywere described above in the discussion of. That description also applies toand is not repeated here.

100 150 100 100 150 150 1 FIG.B The antenna componentB example shown inalso includes a reference plane, which may be situated at any convenient location (e.g., the feed point where a transmission line connects to the overall antenna, which could be the antenna componentB itself or an antenna that incorporates the antenna componentB). The reference planecan have any suitable physical form (e.g., it can be a layer of a printed circuit board (PCB), etc.). The reference planecan be defined in terms of the physical placement of the antenna (e.g., the ground plane in a monopole antenna or a specific point along a directional antenna array).

1 FIG.B 110 114 140 150 114 140 150 114 140 150 114 110 140 150 114 140 150 114 140 150 As will be appreciated from, the selector-switch circuitA, and specifically the state of the memory cellA, determines whether there is a path from the antenna elementA to the reference plane. When the memory cellA is in a low-resistance state, it acts as a closed switch, thereby providing the antenna elementA with a path to the reference plane, and when the memory cellA is in a high-resistance state, it acts as an open switch, thereby substantially blocking the path between the antenna elementA and the reference plane. Similarly, the state of the memory cellB of the selector-switch circuitB determines whether there is a path from the antenna elementB to the reference plane(i.e., when the memory cellB is in a low-resistance state, the antenna elementB has a path to the reference plane, and when the memory cellB is in a high-resistance state, it substantially blocks the path between the antenna elementB and the reference plane).

100 160 118 110 150 160 118 110 150 160 120 150 160 160 160 160 160 160 160 160 160 100 130 120 120 120 140 140 160 160 160 140 140 140 140 1 FIG.B The antenna componentB also includes a capacitorA situated on a path between the inner terminalA of the selector-switch circuitA and the reference plane, a capacitorB situated on a path between the inner terminalB of the selector-switch circuitB and the reference plane, and a capacitorC situated on a path between the wireA and the reference plane. An implementation may include all of the capacitorA, the capacitorB, and the capacitorC, or it may include fewer than all of them. Similarly, if present, the capacitorA, capacitorB, and/or capacitorC can be situated differently than shown in, as explained herein. The purpose of the capacitorA, the capacitorB, and the capacitorC in the antenna componentB is to substantially prevent DC signals (e.g., generated by the control circuitryand flowing on the wireA, wireB, and/or wireC) from flowing through the antenna elementA and the antenna elementB. In other words, the capacitorA, capacitorB, and capacitorC suppress DC signals that might otherwise flow through the antenna elementA and antenna elementB by interrupting the DC path between the control/selection circuitry and the antenna elementA and antenna elementB.

1 FIG.A 1 FIG.B 120 120 120 120 120 120 120 120 120 110 110 130 140 140 110 120 140 As explained in the discussion of, the wireA, the wireB, and/or the wireC can be high-inductance wires. Alternatively or in addition, low-pass filters can be situated on or coupled to wireA, the wireB, and/or the wireC, and/or inductors can be situated on or coupled to the wireA, the wireB, and/or the wireC to isolate the selector-switch circuitA, selector-switch circuitB, and/or control circuitryfrom RF signals fed to or flowing through the antenna elementA and antenna elementB. Thus, in the configuration shown in, the RF path and the DC path can be isolated from each other, thereby isolating signals flowing through the switching fabric (e.g., the selector-switch circuitsand the wires) from signals flowing through the antenna elements.

1 FIG.C 1 FIG.C 1 FIG.B 1 FIG.C 1 FIG.C 100 112 112 114 114 130 140 118 110 140 118 110 120 150 160 140 118 140 118 is a diagram of another antenna componentC in accordance with some embodiments. Many of the elements of(e.g., the selectorA, selectorB, memory cellA, memory cellB, and control circuitry) are as shown and described above in the context of. That explanation applies as well toand is not repeated here. In, the antenna elementA is coupled to the inner terminalA of the selector-switch circuitA, the antenna elementB is coupled to the inner terminalB of the selector-switch circuitB, and the wireA is coupled to the reference planethrough a capacitor. Coupling the antenna elementA to the inner terminalA and coupling the antenna elementB to the inner terminalB can be advantageous to reduce losses and/or support different circuit topologies.

1 FIG.D 1 FIG.D 1 FIG.A 1 FIG.D 100 100 110 112 114 120 110 116 116 120 110 116 116 120 120 130 140 110 118 116 116 120 150 160 114 110 140 150 114 140 150 114 140 150 114 is a diagram illustrating an antenna componentD in accordance with some embodiments.illustrates how the various hardware elements of the antenna componentD can be connected or coupled together. In the illustrated example, a selector-switch circuit(comprising a selectorand a memory cellas described above in the context of) is situated as shown. The wireA is shown situated below the selector-switch circuit(e.g., connected to either the outer terminalA or outer terminalB), and the wireB is shown situated over the selector-switch circuit(e.g., connected to either the outer terminalB or the outer terminalA). The wireA and wireB are coupled to the control circuitrydescribed above (not illustrated into avoid obscuring the drawing). An antenna elementis coupled to the selector-switch circuitas shown (e.g., to an inner terminal, or to the outer terminalA or outer terminalB). The wireA is coupled to a reference planethrough a capacitor. Depending on the state of the memory cellof the selector-switch circuit, there either is or is not an RF path between the antenna elementand the reference plane(i.e., when the memory cellis in the low resistance state, there is a an RF path from the antenna elementto the reference plane, and when the memory cellis in the high-resistance state, the RF path from the antenna elementto the reference planeis substantially blocked by the memory cell).

1 FIG.E 1 FIG.E 1 FIG.D 100 110 140 100 110 140 110 140 110 120 120 110 120 120 160 120 150 is a diagram illustrating an antenna componentE in accordance with some embodiments.is similar to, except that it shows two selector-switch circuitsand two antenna elements. Specifically, the antenna componentE includes a selector-switch circuitA coupled to an antenna elementA and a selector-switch circuitB coupled to an antenna elementB. The selector-switch circuitA is shown situated between and coupled to the wireA and the wireB, and the selector-switch circuitB is shown situated between and coupled to the wireA and the wireC. A capacitoris situated between the wireA and the reference planeto isolate the DC and RF paths as described above.

120 120 120 130 114 110 120 120 130 114 110 120 120 114 114 130 140 150 140 150 1 FIG.E The wireA, wireB, and wireC are coupled to control circuitry(not illustrated into avoid obscuring the drawing), which can then select and set/alter the memory cellA of the selector-switch circuitA using the wireA and the wireB. Likewise, the control circuitrycan select and set/alter the memory cellB of the selector-switch circuitB using the wireA and the wireC. By setting the resistances of the memory cellA and memory cellB, the control circuitrycan control whether there is an RF path from the antenna elementA to the reference planeand whether there is an RF path from the antenna elementB to the reference plane.

1 FIG.E 1 FIG.E 1 FIG.E 140 110 120 140 110 120 160 120 150 120 140 120 140 120 Althoughillustrates only two antenna elementsand the associated selector-switch circuitsand wires, it is to be appreciated that an implementation can include many more antenna elements, selector-switch circuits, and wires. It should also be appreciated that althoughillustrates a capacitorsituated between the wireA and the reference plane, there are other ways that the DC signals on the wirescan be substantially prevented from flowing through the antenna elements, as described above. Conversely,suggests that the wireshave high enough inductance to substantially suppress RF signals fed to or flowing through the antenna elementsthat might otherwise flow through the wires, but it is to be appreciated that other techniques (e.g., lowpass filters, inductors, etc.) can be used instead or in addition, as explained above.

100 140 110 130 120 110 120 120 110 120 120 120 110 140 1 1 FIGS.A-E 1 FIG.E The antenna componentsshown inand described above implement addressing/selection of antenna elementsusing switching fabrics in which each selector-switch circuitis controlled by the control circuitryusing a unique pair of wires. For example, with reference to, the selector-switch circuitA is controlled using the wireA and wireB, and the selector-switch circuitB is controlled using the wireA and the wireC. Conversely, in the illustrated example, each unique pair of wiresselects only one of the selector-switch circuitsand its respective antenna element.

100 140 130 140 140 As will be appreciated by those having ordinary skill in the art in light of the teachings herein, the structural components of an antenna componentcan be arranged in a variety of ways to allow the elements of the antenna component that select and configure the antenna elements(the switching fabric and control circuitry) to be coupled to the antenna elementsin a way that substantially isolates the RF path through the antenna elementsfrom the DC path used by the select/configure circuitry (and vice versa). The examples presented herein are not intended to be limiting.

2 FIG.A 2 FIG.A 2 FIG.A 2 FIG.A 2 FIG.A 170 170 170 170 120 110 120 120 120 120 120 120 120 120 120 120 120 120 120 170 140 120 170 is a diagram illustrating an example of a larger switching fabricin accordance with some embodiments. The switching fabricexample shown inis a cross-point architecture structure, but it is to be appreciated that, as stated above, the switching fabriccan have other architectures. The switching fabricofincludes a plurality of wiresand a plurality of selector-switch circuits. Five of the individual wiresare labeled in, namely the wireA, the wireB, the wireC, the wireD, and the wireE. For convenience of illustration,shows a row/column structure with some of the wires, including the wireA and wireD, selecting rows and the rest of the wires, including the wireB, wireC, and wireE, selecting columns, but there is no requirement for a switching fabricto have a row/column structure. Because the antenna elementsare not required to be in a planar arrangement (e.g., they could be on a curved or other non-flat surface, or generally situated in a non-planar three-dimensional configuration), the wiresof the switching fabriccan have any convenient orientation or layout in an implementation.

120 130 130 1 1 FIGS.A-C 2 FIG.A The plurality of wiresis coupled to control circuitry(e.g., as illustrated in). As in other drawings, the control circuitryis not illustrated into avoid obscuring the drawing.

110 110 112 114 1 1 1 1 1 FIGS.A,B,C,D, andE 1 1 FIGS.A andB The selector-switch circuitscan be as described above and illustrated in any or all of. Specifically, each of the selector-switch circuitscan include a selectorand a memory cellcoupled in series (e.g., as shown and described above in the context of).

170 110 130 120 110 110 A key characteristic of the switching fabricis that each selector-switch circuitis addressable (e.g., selectable by the control circuitry) using a unique pair of wires. In some embodiments, each unique pair of wires selects no more than one selector-switch circuit. It is to be appreciated that it is not a requirement for each unique pair of wires to select no more than one selector-switch circuit.

120 120 110 120 120 110 120 120 110 110 120 120 110 120 120 110 120 120 110 120 120 120 110 2 FIG.A For example, the wireA and wireB select the selector-switch circuitA, the wireA and wireC select the selector-switch circuitB, and the wireD and wireE select the selector-switch circuitC. Likewise, the selector-switch circuitA is selectable only by the wireA and the wireB, the selector-switch circuitB is selectable only by the wireA and wireC, and the selector-switch circuitC is selectable only by the wireD and wireE. It can be verified by inspection ofthat each of the selector-switch circuitsis addressable by a unique combination of wires, and, conversely, each unique combination of a “row” wireand a “column” wireselects only one selector-switch circuit.

140 1 140 130 110 170 100 1 1 1 1 FIGS.A,B,C,D 2 FIG.A In combination with the antenna elementsand RF and DC isolation techniques described above in the context of, and/orE (e.g., techniques using hardware elements (e.g., capacitors, inductors, low-pass filters, split-ring resonators, etc.) to isolate the RF path among the antenna elementsfrom the DC path used by the control circuitryto select/deselect/control the selector-switch circuits, and vice versa), the switching fabricofcan be included in an antenna componentto provide a flexible, integrated implementation.

2 FIG.B 2 FIG.B 2 FIG.B 1 1 FIGS.D andE 2 FIG.B 2 FIG.B 2 FIG.B 170 170 170 170 110 120 110 120 121 120 110 121 120 110 121 121 130 110 is another illustration of an example of a switching fabricin accordance with some embodiments. The switching fabricexample shown inis another cross-point architecture structure, but it is to be appreciated that, as stated above, the switching fabriccan have other architectures.can be considered a top view of the switching fabric, with the selector-switch circuitssituated as shown in, with one of the wiressituated above the selector-switch circuit, and the other of the wiressituated below it. In, a first plurality of wiresA, shown as column wires, is situated under the selector-switch circuits, and a second plurality of wiresB, shown as row wires, is situated over the selector-switch circuits. The first plurality of wiresA and second plurality of wiresB are coupled to control circuitry, which is not illustrated in. To avoid obscuring the drawing, only two of the selector-switch circuitsare labeled in.

170 140 100 100 170 100 170 140 140 110 190 190 110 140 140 190 121 121 140 190 2 FIG.B 3 FIG.A 2 FIG.B 2 FIG.B 3 FIG.A The switching fabricofcan be augmented by other hardware elements (e.g., antenna elements) to form an antenna component.is an illustration of an antenna componentF that uses a switching fabricsuch as the example shown inin accordance with some embodiments. The antenna componentF includes the switching fabricofoverlaid by and coupled to a plurality of antenna elements. To avoid obscuring the drawing, only one antenna elementand only one selector-switch circuitare labeled with reference numerals.also includes a plurality of connections, shown in thicker lines. The plurality of connectionscan be used in combination with the selector-switch circuitsto connect antenna elementsto each other (e.g., create an RF path between antenna elements) in a variety of patterns. Although not illustrated, each of the plurality of connectionscan include hardware to substantially prevent DC signals on the first plurality of wiresA and/or second plurality of wiresB from flowing through the antenna elements. For example, each plurality of connectionscan include a capacitor to substantially block DC signals.

3 FIG.B 3 FIG.A 3 FIG.B 3 FIG.B 110 140 110 140 140 110 140 140 130 120 120 110 114 110 130 120 120 114 140 140 140 140 140 140 is an example to illustrate how the selector-switch circuitsofcan be configured to connect antenna elementsto each other. In the example of, the selector-switch circuitA is situated between an antenna elementA and an antenna elementB, and a selector-switch circuitB is situated between the antenna elementB and an antenna elementC. The control circuitry(not illustrated in) can use the wireA and the wireC to select the selector-switch circuitA and set the state of the associated corresponding memory cellto the low-resistance state (closed switch, indicated by shading the selector-switch circuitA black). Likewise, the control circuitrycan use the wireB and the wireD to set the state of the associated corresponding memory cellto the low-resistance (closed) state. By doing so, the antenna elementA, antenna elementB, and antenna elementC can be coupled together. In other words, the antenna elementA, antenna elementB, and antenna elementC can be configured so that they appear to be combined.

140 140 110 140 140 3 FIG.B In some embodiments, theA// and antenna elementB inform parts of a split-ring resonator, such as two concentric arc segments. By configuring the selector-switch circuitA situated between the antenna elementA and the antenna elementB into a low-resistance state, the arc segments are coupled together.

140 140 110 3 FIG.B In some embodiments, the antenna elementA and the antenna elementB incorrespond to two nodes in a resonant circuit, such as, for example, the two ends of an arc segment of a split-ring resonator. By configuring the selector-switch circuitA situated between the two nodes, the properties of the resonant circuit are changed. For example, by connecting the ends of the arc segment, the arc is closed, and the resonator is detuned compared to a gapped split-ring resonator.

4 FIG.A 100 120 140 120 100 120 120 120 120 130 120 120 114 110 140 140 130 120 120 114 110 140 120 120 114 110 140 120 120 114 110 shows an antenna componentG that uses additional wiresto allow flexibility in configuring the antenna elements. Instead of one “row” wire, the antenna componentG has three “row” wires, namely the wireA, wireB, and wireC. The control circuitry(not illustrated to avoid obscuring the drawing) can use the wireA and wireD to set the memory cellA of the selector-switch circuitA to the low-resistance state to couple the antenna elementA and antenna elementB together. Similarly, the control circuitrycan use the wireB and wireE to set the memory cellB of the selector-switch circuitB to the low-resistance state to couple in the antenna elementC, and the wireC and the wireF to set the memory cellof the selector-switch circuitC to the low-resistance state to couple in the antenna elementD. But using the wireA and the wireG to set the memory cellof the selector-switch circuitD to the low-resistance state causes a loop/short-circuit.

4 FIG.B 4 FIG.A 4 FIG.B 100 160 110 110 160 140 140 140 140 140 140 110 140 illustrates one example solution to the problem ofin accordance with some embodiments. As shown in, the antenna componentH includes a capacitoris situated between the selector-switch circuitB and the selector-switch circuitC. The capacitorinterrupts the DC path and allows the antenna elementA and antenna elementB to be selected and coupled together, and the antenna elementC and antenna elementD to be selected and coupled together independently of the antenna elementA and antenna elementB. This approach can be expanded to include various combinations of the selector-switch circuitsand antenna elements.

190 140 100 140 110 120 100 120 120 110 110 140 140 190 110 190 140 140 190 110 190 114 110 110 110 3 FIG.B 5 FIG. 3 FIG.B 5 FIG. The use of a plurality of connectionsas described above in the discussion ofcan be expanded to allow additional subsets of antenna elementsto be coupled together.is an illustration of an example of an antenna componentJ that allows additional combinations of antenna elementsto be coupled together in accordance with some embodiments. As shown, additional selector-switch circuitsand additional wirescan be included in the antenna componentJ to provide additional flexibility. For example, in addition to the wiresshown in,shows the addition of a wireZ, which is coupled to additional selector-switch circuits, including the selector-switch circuitB. In the illustrated example, the antenna elementA is coupled to the antenna elementB through the connectionA, the selector-switch circuitA, and the connectionB. The antenna elementB is coupled to the antenna elementC through the connectionC, the selector-switch circuitB, and the connectionD. The illustrated configuration can be accomplished by setting the memory cellsin the selector-switch circuitA and the selector-switch circuitB to the low-resistance state (indicated as the selector-switch circuitsbeing shaded black).

6 FIG. 6 FIG. 100 100 130 170 140 170 140 140 170 140 180 180 140 180 180 140 180 is a diagram illustrating components of another antenna componentK in accordance with some embodiments. The antenna componentK includes control circuitrycoupled to a switching fabric(e.g., as shown in the figures and described above), which is coupled to antenna elements. The switching fabriccan be directly connected to the antenna elements, or it can be connected through intervening components (e.g., capacitors or other elements that can isolate the RF path through the antenna elementsfrom the DC path(s) through the switching fabric). In the example of, the antenna elementsare coupled to a phase shifter. As will be appreciated, a phase shifteris a device or component used (e.g., in phased array antennas) to control the phase of the RF signal feeding some or all of the antenna elements. The phase shiftercan introduce a controlled delay in the RF signal, which effectively changes the phase angle of the signal, which alters the constructive and destructive interference patterns in the radiated wavefront. The phase shiftercan apply different phase shifts to the antenna elements(collectively or individually) and electronically steer the direction and shape of the main radiation beam. Thus, by adjusting the phase(s) of the RF signal, the phase shifterallows the antenna to steer its beam in different directions without physically moving the antenna.

180 If included, the phase shiftercan be an analog phase shifter (e.g., a varactor diode phase shifter, a ferrite phase shifter, etc.), a digital phase shifter (e.g., comprising switches, delay lines, and/or digital circuits (e.g., digital signal processors)), a mechanical phase shifter (e.g., to physically change the length of the transmission path), or a liquid crystal or MEMS phase shifter.

170 130 100 100 200 100 202 200 204 110 7 FIG. As explained above, the switching fabricdescribed herein allows the control circuitryto configure the antenna componentand/or adjust the configuration of the antenna component.is a flow diagram of an example of a methodof using an antenna componentin accordance with some embodiments. At block, the methodbegins. At block, a configuration of the selector-switch circuitsis determined. For example, the configuration may be a pre-set configuration for a particular geography/location, time of day, expected or actual signal strength, jamming condition, interference condition, or weather condition. The configuration can be determined in any suitable manner. In some embodiments, the configuration is determined by performing a calculation. In some embodiments, the configuration is determined by retrieving the configuration from memory (e.g., a database).

206 130 120 110 204 130 110 120 112 112 110 114 110 130 140 100 th At block, the control circuitryconfigures the antenna component using the wiresto configure the selector-switch circuitsin accordance with the configuration determined at block. As explained above, the control circuitrycan address individual selector-switch circuitsusing unique pairs of wires(e.g., in the case that the selectorcomprises a threshold switching device, by applying a voltage greater than Vto cause the selectorof the selector-switch circuitto be in the conductive/on state, thereby enabling the corresponding memory cellto be set/modified). As explained above, by controlling/setting the selector-switch circuits, the control circuitrycan configure the antenna elementsof the antenna component.

208 100 100 208 100 At block, optionally, the configuration of the antenna componentis adjusted. For example, it may be determined after some elapsed period that the initial configuration of the antenna componentis suboptimal, or performance could or should be improved. Thus, at block, the configuration can be adjusted (e.g., optimized), if desired. The adjustment of the antenna componentcan be based on any appropriate factor. For example, the adjustment can be based at least in part on a signal strength (e.g., of a received signal), the radiated power of the antenna, interference suppression, jamming suppression, environmental conditions (e.g., temperature, humidity, presence of rain or fog), etc. The configuration can be adjusted to modify or set the antenna's gain, directivity, bandwidth, frequency (or frequency range), size (actual or apparent), radiation pattern (e.g., beamwidth, sidelobe levels, steering, etc.), polarization (e.g., linear, circular, elliptical, cross-polarization, etc.), or efficiency.

210 200 At block, the methodends.

2 FIG.A 110 170 For simplicity, this document sometimes illustrates planar arrangements (e.g.,) in which elements (e.g., selector-switch circuits) are situated in a grid pattern having rows and columns. It is to be appreciated, however, that the teachings are not limited to grid or planar arrangements and can be applicable to other configurations, such as, for example, linear arrangements, circular or triangular grids, or three-dimensional arrangements. It is not a requirement for a switching fabricto be planar or in a grid arrangement.

140 140 Similarly, it is to be appreciated the disclosures are applicable to a variety of antenna elementsand types of antennas (e.g., dipole antennas, microstrip antennas, etc.). It will be understood that the selected antenna elementsmay depend on a variety of factors, such as frequency range.

140 2 2 2 2 140 Although it may be convenient in an implementation to space the antenna elementsby about half the wavelength (/) of the operating frequency, the disclosed techniques are not limited to/between antenna elements.

140 140 As explained above, the teachings herein can be used with techniques such as phase shifting (e.g., applying different phase shifts to signals feeding different antenna elementsin the array to steer the direction of the main beam). In addition, or alternatively, the techniques described herein can be used with amplitude weighting (e.g., adjusting the amplitudes of the signals at different antenna elementsto control the shape of the radiation pattern, control side lobes, adjust the main lobe's strength, etc.), digital beamforming (e.g., using digital signal processing techniques to control the beam pattern substantially in real-time), and other techniques.

100 The antenna componentsdescribed and claimed herein can be used in a variety of antenna types. For example, they can be used in a dipole antenna, a monopole antenna, a loop antenna, a Yagi-Uda antenna, a patch antenna, a parabolic antenna, or a phased array antenna.

In the foregoing description and in the accompanying drawings, specific terminology has been set forth to provide a thorough understanding of the disclosed embodiments. In some instances, the terminology or drawings may imply specific details that are not required to practice the invention.

To avoid obscuring the present disclosure unnecessarily, well-known components are shown in block diagram form and/or are not discussed in detail or, in some cases, at all.

Unless otherwise specifically defined herein, all terms are to be given their broadest possible interpretation, including meanings implied from the specification and drawings and meanings understood by those skilled in the art and/or as defined in dictionaries, treatises, etc. As set forth explicitly herein, some terms may not comport with their ordinary or customary meanings.

As used in the specification and the appended claims, the singular forms “a,” “an” and “the” do not exclude plural referents unless otherwise specified. The word “or” is to be interpreted as inclusive unless otherwise specified. Thus, the phrase “A or B” is to be interpreted as meaning all of the following: “both A and B,” “A but not B,” and “B but not A.” Any use of “and/or” herein does not mean that the word “or” alone connotes exclusivity.

As used in the specification and the appended claims, phrases of the form “at least one of A, B, and C,” “at least one of A, B, or C,” “one or more of A, B, or C,” and “one or more of A, B, and C” are interchangeable, and each encompasses all of the following meanings: “A only,” “B only,” “C only,” “A and B but not C,” “A and C but not B,” “B and C but not A,” and “all of A, B, and C.”

To the extent that the terms “include(s),” “having,” “has,” “with,” and variants thereof are used in the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term “comprising,” i.e., meaning “including but not limited to.” The terms “exemplary” and “embodiment” are used to express examples, not preferences or requirements.

The term “coupled” is used herein to express a direct connection/attachment as well as a connection/attachment through one or more intervening elements or structures.

The terms “over,” “under,” “between,” and “on” as used herein refer to a relative position of one feature with respect to other features. For example, one feature disposed “over” or “under” another feature may be directly in contact with the other feature or may have intervening material, components, or features. Moreover, one feature disposed “between” two features may be directly in contact with the two features or may have one or more intervening features, components, or materials. In contrast, a first feature “on” a second feature is in contact with that second feature.

The term “substantially” is used to describe a structure, configuration, dimension, etc. that is largely or nearly as stated, but, due to manufacturing tolerances and the like, may in practice result in a situation in which the structure, configuration, dimension, etc. is not always or necessarily precisely as stated. For example, describing two lengths as “substantially equal” means that the two lengths are the same for all practical purposes, but they may not (and need not) be precisely equal at sufficiently small scales. As another example, a structure that is “substantially vertical” would be considered to be vertical for all practical purposes, even if it is not precisely at 90 degrees relative to horizontal.

The drawings are not necessarily to scale, and the dimensions, shapes, and sizes of the features may differ substantially from how they are depicted in the drawings.

Although specific embodiments have been disclosed, it will be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the disclosure. For example, features or aspects of any of the embodiments may be applied, at least where practicable, in combination with any other of the embodiments or in place of counterpart features or aspects thereof.

Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.